I have a problem with select my square.
I code it by Red Book way but the result of picking my square is not precise too: the result of picking is true when I pick little out of it (1-2pixel). Which reasons? Is it ok?

Picking using selection implies a pick region of the specified size. Try reducing this size picking can be really precice but you need to reduce the pick region dimensions accordingly. Ultimately you have control of this, the GLU functions are just utilities that adjust the scope of the rendered region you can do this yourself using your own transformations.

the selection is not precise if I translate (e.g.
glTranslatef(45,0,0,1) ) the square.The problem is only on a side of square…Why?